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<pre><span class="sourceLineNo">001</span><a name="line.1"></a>
<span class="sourceLineNo">002</span>/*<a name="line.2"></a>
<span class="sourceLineNo">003</span> * Copyright (C) 2011 Archie L. Cobbs. All rights reserved.<a name="line.3"></a>
<span class="sourceLineNo">004</span> *<a name="line.4"></a>
<span class="sourceLineNo">005</span> * $Id: RetryTransaction.html 906 2014-07-30 00:09:06Z archie.cobbs $<a name="line.5"></a>
<span class="sourceLineNo">006</span> */<a name="line.6"></a>
<span class="sourceLineNo">007</span><a name="line.7"></a>
<span class="sourceLineNo">008</span>package org.dellroad.stuff.spring;<a name="line.8"></a>
<span class="sourceLineNo">009</span><a name="line.9"></a>
<span class="sourceLineNo">010</span>import java.lang.annotation.Documented;<a name="line.10"></a>
<span class="sourceLineNo">011</span>import java.lang.annotation.ElementType;<a name="line.11"></a>
<span class="sourceLineNo">012</span>import java.lang.annotation.Inherited;<a name="line.12"></a>
<span class="sourceLineNo">013</span>import java.lang.annotation.Retention;<a name="line.13"></a>
<span class="sourceLineNo">014</span>import java.lang.annotation.RetentionPolicy;<a name="line.14"></a>
<span class="sourceLineNo">015</span>import java.lang.annotation.Target;<a name="line.15"></a>
<span class="sourceLineNo">016</span><a name="line.16"></a>
<span class="sourceLineNo">017</span>/**<a name="line.17"></a>
<span class="sourceLineNo">018</span> * An annotation for {@link org.springframework.transaction.annotation.Transactional @Transactional} methods that<a name="line.18"></a>
<span class="sourceLineNo">019</span> * want to have transactions automatically retried when they fail due to a transient exception. A transient exception<a name="line.19"></a>
<span class="sourceLineNo">020</span> * is one that Spring would translate into a<a name="line.20"></a>
<span class="sourceLineNo">021</span> * {@link org.springframework.dao.TransientDataAccessException TransientDataAccessException}.<a name="line.21"></a>
<span class="sourceLineNo">022</span> * &lt;/p&gt;<a name="line.22"></a>
<span class="sourceLineNo">023</span> *<a name="line.23"></a>
<span class="sourceLineNo">024</span> * &lt;p&gt;<a name="line.24"></a>
<span class="sourceLineNo">025</span> * This automatic retry logic is very handy for solving the problem of transient deadlocks that can occur in complex Java/ORM<a name="line.25"></a>
<span class="sourceLineNo">026</span> * applications. Due to the ORM layer hiding the details of the underlying data access patterns, it's often difficult<a name="line.26"></a>
<span class="sourceLineNo">027</span> * to design Java/ORM applications such that transient deadlocks at the database layer can't occur. Since these<a name="line.27"></a>
<span class="sourceLineNo">028</span> * deadlocks can often be dealt with simply by retrying the transaction, having retry logic automatically applied can<a name="line.28"></a>
<span class="sourceLineNo">029</span> * eliminate this problem.<a name="line.29"></a>
<span class="sourceLineNo">030</span> * &lt;/p&gt;<a name="line.30"></a>
<span class="sourceLineNo">031</span> *<a name="line.31"></a>
<span class="sourceLineNo">032</span> * &lt;p&gt;<a name="line.32"></a>
<span class="sourceLineNo">033</span> * Note, beans involved in transactions should either be stateless, or be prepared to rollback any state changes on transaction<a name="line.33"></a>
<span class="sourceLineNo">034</span> * failure; of course, this is true whether or not transactions are automatically being retried, but adding automatic retry<a name="line.34"></a>
<span class="sourceLineNo">035</span> * can magnify pre-existing bugs of that nature.<a name="line.35"></a>
<span class="sourceLineNo">036</span> * &lt;/p&gt;<a name="line.36"></a>
<span class="sourceLineNo">037</span> *<a name="line.37"></a>
<span class="sourceLineNo">038</span> * &lt;p&gt;<a name="line.38"></a>
<span class="sourceLineNo">039</span> * The {@link RetryTransaction @RetryTransaction} annotation is ignored unless all of the following conditions are satisfied:<a name="line.39"></a>
<span class="sourceLineNo">040</span> * &lt;ul&gt;<a name="line.40"></a>
<span class="sourceLineNo">041</span> *  &lt;li&gt;<a name="line.41"></a>
<span class="sourceLineNo">042</span> *      The method (and/or the containing type) must be annotated with both<a name="line.42"></a>
<span class="sourceLineNo">043</span> *      {@link org.springframework.transaction.annotation.Transactional @Transactional}<a name="line.43"></a>
<span class="sourceLineNo">044</span> *      and {@link RetryTransaction @RetryTransaction}<a name="line.44"></a>
<span class="sourceLineNo">045</span> *  &lt;/li&gt;<a name="line.45"></a>
<span class="sourceLineNo">046</span> *  &lt;li&gt;<a name="line.46"></a>
<span class="sourceLineNo">047</span> *      The {@link org.springframework.transaction.annotation.Transactional @Transactional} annotation must have<a name="line.47"></a>
<span class="sourceLineNo">048</span> *      {@linkplain org.springframework.transaction.annotation.Transactional#propagation propagation} set to either<a name="line.48"></a>
<span class="sourceLineNo">049</span> *      {@link org.springframework.transaction.TransactionDefinition#PROPAGATION_REQUIRED PROPAGATION_REQUIRED} or<a name="line.49"></a>
<span class="sourceLineNo">050</span> *      {@link org.springframework.transaction.TransactionDefinition#PROPAGATION_REQUIRES_NEW PROPAGATION_REQUIRES_NEW}<a name="line.50"></a>
<span class="sourceLineNo">051</span> *      (other propagation values do not involve creating new transactions).<a name="line.51"></a>
<span class="sourceLineNo">052</span> *  &lt;/li&gt;<a name="line.52"></a>
<span class="sourceLineNo">053</span> *  &lt;li&gt;<a name="line.53"></a>
<span class="sourceLineNo">054</span> *      In the case of<a name="line.54"></a>
<span class="sourceLineNo">055</span> *      {@link org.springframework.transaction.TransactionDefinition#PROPAGATION_REQUIRED PROPAGATION_REQUIRED} propagation,<a name="line.55"></a>
<span class="sourceLineNo">056</span> *      there must not be a transaction already open in the calling thread. In other words, the invoked method must<a name="line.56"></a>
<span class="sourceLineNo">057</span> *      be the one responsible for creating the transaction.<a name="line.57"></a>
<span class="sourceLineNo">058</span> *  &lt;/li&gt;<a name="line.58"></a>
<span class="sourceLineNo">059</span> *  &lt;li&gt;<a name="line.59"></a>
<span class="sourceLineNo">060</span> *      The method's class must be woven (either at build time or runtime) using the<a name="line.60"></a>
<span class="sourceLineNo">061</span> *      &lt;a href="http://www.eclipse.org/aspectj/doc/released/faq.php#compiler"&gt;AspectJ compiler&lt;/a&gt;<a name="line.61"></a>
<span class="sourceLineNo">062</span> *      with the {@code RetryTransactionAspect} aspect (included in the &lt;code&gt;dellroad-stuff&lt;/code&gt; JAR file).<a name="line.62"></a>
<span class="sourceLineNo">063</span> *  &lt;/li&gt;<a name="line.63"></a>
<span class="sourceLineNo">064</span> *  &lt;li&gt;<a name="line.64"></a>
<span class="sourceLineNo">065</span> *      The {@code RetryTransactionAspect} aspect must be configured with a<a name="line.65"></a>
<span class="sourceLineNo">066</span> *      {@link org.springframework.dao.support.PersistenceExceptionTranslator PersistenceExceptionTranslator} appropriate for<a name="line.66"></a>
<span class="sourceLineNo">067</span> *      the ORM layer being used. The simplest way to do this is to include the aspect in your Spring application context,<a name="line.67"></a>
<span class="sourceLineNo">068</span> *      for example:<a name="line.68"></a>
<span class="sourceLineNo">069</span> *      &lt;pre&gt;<a name="line.69"></a>
<span class="sourceLineNo">070</span> *<a name="line.70"></a>
<span class="sourceLineNo">071</span> *      &amp;lt;bean class="org.dellroad.stuff.spring.RetryTransactionAspect" factory-method="aspectOf"<a name="line.71"></a>
<span class="sourceLineNo">072</span> *        p:persistenceExceptionTranslator-ref="myJpaDialect"/&amp;gt;<a name="line.72"></a>
<span class="sourceLineNo">073</span> *      &lt;/pre&gt;This also gives you the opportunity to change the default values for {@link #maxRetries}, {@link #initialDelay},<a name="line.73"></a>
<span class="sourceLineNo">074</span> *      and {@link #maximumDelay}, which are applied when not explicitly overridden in the annotation, for example:<a name="line.74"></a>
<span class="sourceLineNo">075</span> *      &lt;pre&gt;<a name="line.75"></a>
<span class="sourceLineNo">076</span> *<a name="line.76"></a>
<span class="sourceLineNo">077</span> *      &amp;lt;bean class="org.dellroad.stuff.spring.RetryTransactionAspect" factory-method="aspectOf"<a name="line.77"></a>
<span class="sourceLineNo">078</span> *        p:persistenceExceptionTranslator-ref="myJpaDialect" p:maxRetriesDefault="2"<a name="line.78"></a>
<span class="sourceLineNo">079</span> *        p:initialDelayDefault="25" p:maximumDelayDefault="5000"/&amp;gt;<a name="line.79"></a>
<span class="sourceLineNo">080</span> *      &lt;/pre&gt;<a name="line.80"></a>
<span class="sourceLineNo">081</span> *  &lt;/li&gt;<a name="line.81"></a>
<span class="sourceLineNo">082</span> * &lt;/ul&gt;<a name="line.82"></a>
<span class="sourceLineNo">083</span> *<a name="line.83"></a>
<span class="sourceLineNo">084</span> * &lt;p&gt;<a name="line.84"></a>
<span class="sourceLineNo">085</span> * Logging behavior: Normal activity is logged at trace level, retries are logged at debug level, and errors are logged<a name="line.85"></a>
<span class="sourceLineNo">086</span> * at error level.<a name="line.86"></a>
<span class="sourceLineNo">087</span> * &lt;/p&gt;<a name="line.87"></a>
<span class="sourceLineNo">088</span> *<a name="line.88"></a>
<span class="sourceLineNo">089</span> * &lt;p&gt;<a name="line.89"></a>
<span class="sourceLineNo">090</span> * Transactional code can determine the transaction attempt number using the {@link RetryTransactionProvider} interface<a name="line.90"></a>
<span class="sourceLineNo">091</span> * implemented by the aspect. {@link RetryTransactionProvider#getAttemptNumber} method returns the current attempt number<a name="line.91"></a>
<span class="sourceLineNo">092</span> * (1, 2, 3...), or zero if the current thread is not executing within activated retry logic:<a name="line.92"></a>
<span class="sourceLineNo">093</span> *  &lt;blockquote&gt;&lt;pre&gt;<a name="line.93"></a>
<span class="sourceLineNo">094</span> *      import org.dellroad.stuff.spring.RetryTransactionProvider;<a name="line.94"></a>
<span class="sourceLineNo">095</span> *      ...<a name="line.95"></a>
<span class="sourceLineNo">096</span> *<a name="line.96"></a>
<span class="sourceLineNo">097</span> *      &amp;#64;Autowired<a name="line.97"></a>
<span class="sourceLineNo">098</span> *      private RetryTransactionProvider retryTransactionProvider;<a name="line.98"></a>
<span class="sourceLineNo">099</span> *      ...<a name="line.99"></a>
<span class="sourceLineNo">100</span> *<a name="line.100"></a>
<span class="sourceLineNo">101</span> *      &amp;#64;RetryTransaction<a name="line.101"></a>
<span class="sourceLineNo">102</span> *      &amp;#64;Transactional<a name="line.102"></a>
<span class="sourceLineNo">103</span> *      public void doSomething() {<a name="line.103"></a>
<span class="sourceLineNo">104</span> *          ...<a name="line.104"></a>
<span class="sourceLineNo">105</span> *          final int attempt = this.retryTransactionProvider.getAttempt();<a name="line.105"></a>
<span class="sourceLineNo">106</span> *          ...<a name="line.106"></a>
<span class="sourceLineNo">107</span> *      }<a name="line.107"></a>
<span class="sourceLineNo">108</span> *   &lt;/pre&gt;&lt;/blockquote&gt;<a name="line.108"></a>
<span class="sourceLineNo">109</span> * &lt;/p&gt;<a name="line.109"></a>
<span class="sourceLineNo">110</span> *<a name="line.110"></a>
<span class="sourceLineNo">111</span> * @see org.springframework.transaction.annotation.Transactional<a name="line.111"></a>
<span class="sourceLineNo">112</span> */<a name="line.112"></a>
<span class="sourceLineNo">113</span>@Documented<a name="line.113"></a>
<span class="sourceLineNo">114</span>@Inherited<a name="line.114"></a>
<span class="sourceLineNo">115</span>@Retention(RetentionPolicy.RUNTIME)<a name="line.115"></a>
<span class="sourceLineNo">116</span>@Target({ ElementType.TYPE, ElementType.METHOD })<a name="line.116"></a>
<span class="sourceLineNo">117</span>public @interface RetryTransaction {<a name="line.117"></a>
<span class="sourceLineNo">118</span><a name="line.118"></a>
<span class="sourceLineNo">119</span>    /**<a name="line.119"></a>
<span class="sourceLineNo">120</span>     * Default {@linkplain #maxRetries maximum number of retry attempts}, used when the {@link #maxRetries maxRetries}<a name="line.120"></a>
<span class="sourceLineNo">121</span>     * value is not explicitly set in an instance of this annotation.<a name="line.121"></a>
<span class="sourceLineNo">122</span>     * This default value can be overridden by configuring the {@code maxRetriesDefault} property on the aspect itself.<a name="line.122"></a>
<span class="sourceLineNo">123</span>     */<a name="line.123"></a>
<span class="sourceLineNo">124</span>    int DEFAULT_MAX_RETRIES = 4;<a name="line.124"></a>
<span class="sourceLineNo">125</span><a name="line.125"></a>
<span class="sourceLineNo">126</span>    /**<a name="line.126"></a>
<span class="sourceLineNo">127</span>     * Default {@linkplain #initialDelay initial delay}, in milliseconds, used when the {@link #initialDelay initialDelay}<a name="line.127"></a>
<span class="sourceLineNo">128</span>     * value is not explicitly set in an instance of this annotation.<a name="line.128"></a>
<span class="sourceLineNo">129</span>     * This default value can be overridden by configuring the {@code initialDelayDefault} property on the aspect itself.<a name="line.129"></a>
<span class="sourceLineNo">130</span>     */<a name="line.130"></a>
<span class="sourceLineNo">131</span>    long DEFAULT_INITIAL_DELAY = 100;<a name="line.131"></a>
<span class="sourceLineNo">132</span><a name="line.132"></a>
<span class="sourceLineNo">133</span>    /**<a name="line.133"></a>
<span class="sourceLineNo">134</span>     * Default {@linkplain #maximumDelay maximum delay}, in milliseconds, used when the {@link #maximumDelay maximumDelay}<a name="line.134"></a>
<span class="sourceLineNo">135</span>     * value is not explicitly set in an instance of this annotation.<a name="line.135"></a>
<span class="sourceLineNo">136</span>     * This default value can be overridden by configuring the {@code maximumDelayDefault} property on the aspect itself.<a name="line.136"></a>
<span class="sourceLineNo">137</span>     */<a name="line.137"></a>
<span class="sourceLineNo">138</span>    long DEFAULT_MAXIMUM_DELAY = 30 * 1000;<a name="line.138"></a>
<span class="sourceLineNo">139</span><a name="line.139"></a>
<span class="sourceLineNo">140</span>    /**<a name="line.140"></a>
<span class="sourceLineNo">141</span>     * The maximum number of transaction retry attempts.<a name="line.141"></a>
<span class="sourceLineNo">142</span>     *<a name="line.142"></a>
<span class="sourceLineNo">143</span>     * &lt;p&gt;<a name="line.143"></a>
<span class="sourceLineNo">144</span>     * If the transaction fails, it will be retried at most this many times.<a name="line.144"></a>
<span class="sourceLineNo">145</span>     * This limit applies to retries only; it does not apply to the very first attempt, which is always made.<a name="line.145"></a>
<span class="sourceLineNo">146</span>     * So a value of zero means at most one attempt.<a name="line.146"></a>
<span class="sourceLineNo">147</span>     * &lt;/p&gt;<a name="line.147"></a>
<span class="sourceLineNo">148</span>     *<a name="line.148"></a>
<span class="sourceLineNo">149</span>     * &lt;p&gt;<a name="line.149"></a>
<span class="sourceLineNo">150</span>     * If this property is not set explicitly, the default value of {@code -1} indicates that the aspect-wide default value<a name="line.150"></a>
<span class="sourceLineNo">151</span>     * ({@value #DEFAULT_MAX_RETRIES} by default), should be used.<a name="line.151"></a>
<span class="sourceLineNo">152</span>     * &lt;/p&gt;<a name="line.152"></a>
<span class="sourceLineNo">153</span>     */<a name="line.153"></a>
<span class="sourceLineNo">154</span>    int maxRetries() default -1;<a name="line.154"></a>
<span class="sourceLineNo">155</span><a name="line.155"></a>
<span class="sourceLineNo">156</span>    /**<a name="line.156"></a>
<span class="sourceLineNo">157</span>     * The initial delay between retry attempts in milliseconds.<a name="line.157"></a>
<span class="sourceLineNo">158</span>     * After the first transaction failure, we will pause for approximately this many milliseconds.<a name="line.158"></a>
<span class="sourceLineNo">159</span>     * For additional failures we apply a randomized exponential back-off, up to a maximum of {@link #maximumDelay}.<a name="line.159"></a>
<span class="sourceLineNo">160</span>     *<a name="line.160"></a>
<span class="sourceLineNo">161</span>     * &lt;p&gt;<a name="line.161"></a>
<span class="sourceLineNo">162</span>     * If this property is not set explicitly, the default value of {@code -1} indicates that the aspect-wide default value<a name="line.162"></a>
<span class="sourceLineNo">163</span>     * ({@value #DEFAULT_INITIAL_DELAY} milliseconds by default), should be used.<a name="line.163"></a>
<span class="sourceLineNo">164</span>     * &lt;/p&gt;<a name="line.164"></a>
<span class="sourceLineNo">165</span>     */<a name="line.165"></a>
<span class="sourceLineNo">166</span>    long initialDelay() default -1;<a name="line.166"></a>
<span class="sourceLineNo">167</span><a name="line.167"></a>
<span class="sourceLineNo">168</span>    /**<a name="line.168"></a>
<span class="sourceLineNo">169</span>     * The maximum delay between retry attempts in milliseconds.<a name="line.169"></a>
<span class="sourceLineNo">170</span>     * After the first transaction failure, we will pause for approximately {@link #initialDelay} milliseconds.<a name="line.170"></a>
<span class="sourceLineNo">171</span>     * For additional failures we apply a randomized exponential back-off, up to a maximum of this value.<a name="line.171"></a>
<span class="sourceLineNo">172</span>     *<a name="line.172"></a>
<span class="sourceLineNo">173</span>     * &lt;p&gt;<a name="line.173"></a>
<span class="sourceLineNo">174</span>     * If this property is not set explicitly, the default value of {@code -1} indicates that the aspect-wide default value<a name="line.174"></a>
<span class="sourceLineNo">175</span>     * ({@value #DEFAULT_MAXIMUM_DELAY} milliseconds by default), should be used.<a name="line.175"></a>
<span class="sourceLineNo">176</span>     * &lt;/p&gt;<a name="line.176"></a>
<span class="sourceLineNo">177</span>     */<a name="line.177"></a>
<span class="sourceLineNo">178</span>    long maximumDelay() default -1;<a name="line.178"></a>
<span class="sourceLineNo">179</span>}<a name="line.179"></a>
<span class="sourceLineNo">180</span><a name="line.180"></a>




























































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